Render over painted block

[heanous]

My external walls are painted bessa brick (hollow concrete block). I want to achieve a modern rendered look. As rendering over painted surfaces is difficult (as advised by tradesman who quoted my big $$$), I see there are some options:
1 sandblast/strip/angle grind paint down then render
2 apply treatment to surface then render
3 clad over surface (harditex?) then paint with dulux "render effects" or similar to achieve render look
4 clad per 3 then render as per normal

option 3 seems to be cheapest & most suited to diy, though not sure how good the final effect will be. anyone with experience ?

all advice most appreciated...

[outback]

When I renovated our house 'bout 12 years ago part of it was made from ironstone rubble, I extended using bessa bricks, then rendered the lot in sandstone colour render, while the render was still workable it was marked to give the impression of sandstone walls.

The original ironstone had been painted about 800 times with various types of paint, some had been exposed and was badly weathered but the majority was undera verandah and in sorta OK condition.

The plasterer guy chipped-hacked or just plain removed small patches of paint where it was in good nick, then "spatterd" with a gizmo a mixture of cement, bondcrete and water, (I think thats all it was). he assured me that this was all that was needed for the render to "key" to the wall.

Up till now he's right.

[bitingmidge]

Or you could just buy Hardies Panel Clad Stucco Sheets (http://www.jameshardie.com.au/buildingproducts/products_details.asp?cid=35&did=18) and skip the render effects!

Probably the best solution is to use a polymer render from a company like Rockcote (http://www.rockcote.com.au/html/polymerrender.html)

These products are designed for exactly the purpose you have in mind, and should work out a little less costly than a "clean" render job without any of the preparation.

I have used (had a plasterer do the work) Rockote and similar products for many years on projects ranging from medium rise home units, to my own house renovation where the substrates included painted hardiplank, new fc sheet, concrete block and sandstock brick...so I guess it's nothing if not versatile!

Don't go the traditional cement render route over the paint, you may get lucky....but if it was my place it wouldn't last two seconds!

Hope these links help!

P

[wombat47]

We sampled "render effects" on a small section of our painted brick walls (paint in very bad condition with lots of crazing). It came up a treat and has held out well on an exposed west-facing situation.

BUT we realised it was going to be hellishly expensive to do the whole house so abandoned the idea. The paint doesn't go very far at all.

[wombat47]

More on "render" type paints ..

The paint follows the profile of the wall - your wall is going to look like rendered cement blocks. Perhaps not the look you are after.

There's a product called Insulclad - has to been installed by tradesmen and probably hellishly expensive. Have a look at
http://www.nuplexconstruction.com.au/html/insulclad.htm

[bitingmidge]

Wombat 47 wrote:

The paint follows the profile of the wall - your wall is going to look like rendered cement blocks.

The Rockcote product I recommended above certainly does NOT do this. It is NOT a paint type application, although the chemical composition is based on paint material I guess.

Don't confuse paints which are designed to give a rendered texture effect, with genuine polymer renders which are handled like a render (with a trowel) rather than like a paint (with a roller or brush).

Most polymer renders are marketed in a two or three part system, with a heavy filler for the large hollows (where more than 5mm of fill is needed), the "render" coat, and a top coat sometimes known as impact coat.

There are as many different names for each of the components as there are manfacturers!

Hope that is a bit clearer,

Cheers,

P

[wombat47]

To Biting Midge: Ouch!! And I was only referring to my earlier post re our experience with "render effects" paint - No.3 option in the original post. Basically, I wouldn't recommend it.

Can we kiss and make up?

[heanous]

thanks for the many replys.

the polymer render products look good. they are quoting about $60 per bucket which should cover 7 m2, thus about $1500 for the whole house + paint, which would prob be a similar price. $3000 total.

compare this to my option 3 which would be about $2000 of harditex/blueboard + glue ($100) + paint ($1200 - harditex less porous than render). price is about the same but less work then rendering ?

thanks again ...

[bitingmidge]

Dearest Wombat,
:eek:
No nasties intended!!! Just get the old mossie repellant out next time the midge is in town!!

Love and kisses,

P

But I must now give Mr heanous another sting!!

If I am reading correctly you are intending to direct fix the hardistuff to your wall?

I am not sure that GLUEING the harditex is a good thing in an exterior environment. (Well actually I AM sure, and it's not!) Check the manufacturers recommendations VERY carefully. I think you'll find that it needs to be mechanically fixed at regular intervals, and you probably want to consider battening. You also need to carefully consider what you do at corners, sheet junctions and openings. It's all possible but I think in the long run no less work than render.

Proceed with care, I've seen too much of the stuff move over quite a long period of time (years as well as months) to ever trust it without secure fixing.

Having said that, my own rendering skills are not that flash, so I saved for an extra year and hired a render dude.

I have this healthy(?) cynical view of the industry that says if there is a cheaper way of acheiving the same result, every spec builder in the world would be doing it. Currently in my locality, every spec builder is using polymer render.

Cheers, (healthy discussion only, no personal criticism intended!)

P :D :D :D

[heanous]

hey, if i was the fountain of rendering knowledge, i wouldn't be here asking stoopid questions.

i am looking for the least $$$ solution from a number of methods that may (or may not) achieve a similar result.

tanks again.

[bitingmidge]

Sorry if my replies got a bit ahem....firm.

:D :D :D
No such thing as a stupid question in my book, but I've given plenty of stupid answers in my time, and stupid looks are in great demand (mostly 'cause they're the cheapest service I provide I think, and they are really easy to do).

My usual consulting prices are set out for your info, but for the purposes of this forum no charges apply, and there would be a few out there who would be quick to point out that you get what you pay for!!.


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Good luck with the render/boarding up. Don't forget to let us know what you decided, why, and how it turned out eh?

Cheers,

P

[heanous]

do you offer pre-pay & save ... i'll have 3 stupid answers & half a dozen careless whispers. :-)

[schwerdty]

Lads and lasses,
a quick listen up and your problems will be solved.
Buy bagged render from a render supplier.(11-15 bucks a bag) and 50 bags will do a traditional 3 bedroom house.
When you buy it, let them know you are putting it over painted brick and they will sell you an additive that makes it adhere. Ask them as many questions as you can as to application or post here and i will run you through it all from first coat to acrylic top-coat or painted final coat.

Don't know what state you love in, but Insulcon in Dandenong Victoria has brilliantly priced render plus tools and advice. Iv'e used them the past couple of years. Product and price the best around. Top coat is your choice of so many companies. i like MAC Render. but each to their own.

I have to go up to brissie next month to render a two storey joint of 40 squares. Anyone know of some suppliers near the gold coast?